THE "SUMMA THEOLOGICA"

Q. 87.ART.2 THE " SUMMA THEOLOGICA " _2o
that the proposition quoted is true only of separate substances;
because in a sense it is verified in their regard,
and not in regard of other substances, as already stated
(Reply Obi. z).
SECOND ARTICLE.
WHETHER OUR INTELLECT KNOWS THE HABITS OF THE
SOUL B_ THEIR ESSENCE
We proceed thus to the Second Article :_
Obiection I. It would seem that our intellect knows the
habits of the soul by their essence. For Augustine says
(De Trin. xiii. I) : Faith is not seen in the heart _herein it
abides, as the soul of a man may be seen by another from
the movement o] the body; but we know most certainly
that it is there, and conscience proclaims its existence; and
the same principle applies to the other habits of the soul.
Therefore the habits of the soul are not known by their
acts, but by themselves.
Obj. 2. Further, material things outside the soul are
known by their likeness being present in the soul, and are
said therefore to be known by their likenesses. But the
soul's habits are present by their essence in the soul.
Therefore the habits of the soul are known by their essence.
Obi. 3. Further, whatever is the cause of a thing being
such is still more so. But habits and intelligible species
cause things to be known by the soul. Therefore they
are still more known by the soul in themselves.
On the contrary, Habits like powers are the principles of
acts. But as is said (De Anima ii. 4), arts and operations
are logically prior to powers. Therefore in the same way
they are prior to habits; and thus habits, like the powers,
are known by their acts.
I answer that, A habit is a kind of medium between
mere power and mere act. Now, it has been said (A. I)
that nothing is known but as it is actual: therefore so
far as a habit fails in being a perfect act, it falls short in
being of itself knowable, and can be known only by its